Youre right, that is the PC138 with new decals, however I also scaled up the size of the machine to be much closer to the true size of a 238. I used the specifications from Komatsu when doing this to try and get it as accurate as I could. Its not perfect, as scaling machines can be very difficult, however a 238 is also not twice as large as a 138 as you claim, not in operating weight or in any comparable dimension. This machine is also the correct weight for a PC238.
If its not accurate enough to the real life machine for you, that is fine I understand. Like I said, its not perfect. I hope you enjoy some of my other machines!